Fifth-wheel recreation vehicles (or "RV's") and other types of highway trailers are commonly hitched to trucks by means of a trailer kingpin, which is a solid round bar with an annular groove cut into its perimeter. The kingpin is rigidly mounted to the trailer near the front of the trailer, projecting downward, and is adapted to fit into the hitch plate (or "fifth wheel") of a truck to which the trailer is being hitched. The fifth wheel engages the annular groove of the kingpin so as to prevent disengagement, while permitting rotation of the kingpin about its vertical axis so that the truck/trailer combination may negotiate turns.
Theft of trailers, and particularly RV trailers, has been a serious problem for many years. The simplicity of the kingpin hitch apparatus makes it quick and easy for a thief to hitch a truck to an unattended trailer and then abscond therewith. Accordingly, it is desirable to be able to lock the kingpin of so as to prevent engagement with a fifth wheel, and it is particularly desirable to be able to accomplish this with the convenience of a conventional padlock.
A simple attempt to accomplish this objective is illustrated by the prior art locking sleeve shown in FIG. 1 appended hereto. This is a simple cylindrical sleeve having an inner diameter slightly larger than the diameter of a kingpin, and having a pair of circumferential slots separated by a bridging section of the sleeve wall. The sleeve may be slipped over a kingpin, with the circumferential slots coinciding with the annular groove of the kingpin. The shackle of a conventional padlock may then be looped around the bridging section of the sleeve wall so that part of the shackle projects into the annular groove, thereby preventing the sleeve from being slipped off of the kingpin.
The locking sleeve described above is inexpensive to make and simple to use. It has a significant drawback, however, in that most of the padlock shackle is left exposed and readily accessible to bolt cutters or other tools which can quickly shear through the shackle so that the lock and the sleeve may be removed.
U.S. Pat. No. 4,841,756, issued to Curtis on Jun. 27, 1989, discloses one attempt to lock a kingpin by positioning a padlock shackle partly within the kingpin groove while protecting the entire shackle from access to bolt cutters. The Curtis device has a cylindrical sleeve section which may be slipped over a kingpin, plus an attached padlock enclosure body which has a recess shaped to receive and enclose both the shackle and the main body of the padlock. The inner surfaces of the padlock enclosure body define a bulge which the shackle can be positioned over and around. When so positioned, the shackle projects partly into the annular groove of the kingpin, thereby locking the device onto the kingpin. In the addition, the bulge inside the recess is shaped so as to prevent the shackle from passing outwardly over the bulge when the padlock body is inside the recess and engaged with the shackle.
The Curtis device avoids the major disadvantage of the locking sleeve by enclosing the padlock shackle completely within the body of the device, making the shackle inaccessible to bolt cutters. However, the Curtis device has substantial drawbacks of its own. First, it may be used only with a padlock the body and shackle of which are closely matched to the shape of the padlock recess. It cannot be used with padlocks which are too large or too small to fit the recess, or with padlocks which are of a generally suitable size but of an incompatible configuration. Moreover, in order to function satisfactorily with a selected style of padlock, the Curtis device must be fabricated to precise internal shapes and very close tolerances, making it comparatively expensive to manufacture.
For the foregoing reasons, there is a need for an anti-theft locking apparatus:
(a) which utilizes a conventional padlock and provides for the shackle of the padlock to be partially inserted into the annular groove of a kingpin so as to prevent the apparatus from being removed from the kingpin; PA1 (b) which effectively renders the entire length of the padlock shackle inaccessible to bolt cutters; and PA1 (c) which is simple and economical to fabricate compared with other devices achieving the same general objectives. PA1 (a) a lock body having an upper end and a lower end, and defining a cylindrical kingpin opening slightly larger in diameter than the diameter of the kingpin, and further defining a lock body wall surrounding the kingpin opening, said lock body wall defining: PA1 (b) a shackle-retaining element disposed within the trough and spanning substantially across the trough in a direction parallel to the axis of the kingpin opening, said shackle-retaining element being positioned such that the padlock shackle will project partially into the kingpin opening when the shackle is hooked around the shackle-retaining element. PA1 (a) a padlock channel extending partially through the thickness of the lock body wall from said outer surface toward said inner surface; and PA1 (b) a shackle channel contiguous with the padlock channel, and intercepting the kingpin opening so as to form an opening thereinto.